# CVE-2026-63837: net: ena: PHC: Check return code before setting timestamp output

> A local attacker can read uninitialized kernel memory via the ENA network driver's PTP ioctl interface due to missing error checks.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jul 2026
- **Updated:** 19 Jul 2026
- **Also known as:** BELL-CVE-2026-63837, DEBIAN-CVE-2026-63837, GHSA-g7h6-fhch-mvgh, UBUNTU-CVE-2026-63837

## What is CVE-2026-63837?

CVE-2026-63837 is a vulnerability in Linux, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net: ena: PHC: Check return code before setting timestamp output

ena_phc_gettimex64() is setting the output parameter regardless
of whether ena_com_phc_get_timestamp() succeeded or failed.

When ena_com_phc_get_timestamp() returns an error, the timestamp
parameter may contain uninitialized stack memory (e.g., when PHC is
disabled or in blocked state) or invalid hardware values. Passing
these to userspace via the PTP ioctl is both a security issue
(information leak) and a correctness bug.

Fix by checking the return code after releasing the lock and only
setting the output timestamp on success.

## Which versions are affected by CVE-2026-63837?


## How do I fix CVE-2026-63837?

Apply the vendor's patch.

## Is CVE-2026-63837 being exploited?

There is no known exploitation of CVE-2026-63837 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63837 and fix it if it is affected.

What it is: CVE-2026-63837 is a vulnerability in Linux, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-63837 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-63837/ (Markdown: https://insights.sbomify.com/CVE-2026-63837/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63837
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63837
- OSV: https://osv.dev/vulnerability/CVE-2026-63837

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63837/
Summaries are generated and may contain mistakes; the official description above is the record.